Currently, when an article is packed, an air bubble paper or Styrofoam are mostly used to wrap the content thereof, and then place it into a paper box so as to prevent the content from being collided during transportation. However, the air bubble paper can be tightly attached on the surface of the content, but the collision preventing effect is not good. The volume of Styrofoam is bouffant to occupy very much space and is not easy to be decomposed by microorganism,’ it will release poison gas dangerous to human body after incineration process to cause serious environmental pollution. For solving the deficits of the air bubble paper and Styrofoam mentioned above, an air packing bag made from resin is developed; it is sealed by means of hot sealing to form air cylinders and an air filling entrance for air filling is disposed thereon. After air is filled into the air cylinders via the air filling entrance, the air packing bag can then be taken as a cushioning material used in inside packing.
Please refer to FIGS. 1 and 2. FIG. 1 is a schematic view of a conventional air packing bag before air filling. FIG. 2 is a cross sectional view of a conventional air packing bag after air filling. The air packing bag comprises two outer films 21a and 21b folded together, in which the two outer films 21a and 21b are caused to adhere to each other by means of hot sealing, and an air filling passageway 22 and air chambers 23 are also formed by means of hot sealing. The two inner films 25a and 25b are adhered to each other between the two outer films 21a and 21b through hot sealing points 24a, 24b, 24c and 24d and allowed to side-attach onto the outer film 21a and in the meantime, the two inner films 25a and 25b are not adhered to each to form an air passageway 26. When the air in the air filling passageway 22 flows into the air chambers 23 via the air passageway 26 to cause them to be filled with air and expanded, the air in the air chamber 23 to thrust the two inner films 25a and 25b to shield the air chamber 23 so as to prevent the air in the air chamber 23 to be leaked out. For example, Japan utility model patent publishing No. H5-10706 entitled as “Manufacturing method for synthetic resin bag with check valve”, Taiwan Patent No. 587049 titled as “Assembly structure of switch valve of air enclosure and manufacturing apparatus for enclosure with switch valve” and Taiwan Utility Model Patent No. M252680 entitled as “Air packing bag with reverse air locking sheet”.
In such kind type of air enclosure, the air in the air chamber 23 will thrust the hot sealing point 24b to cause it to be loosed gradually to allow a gap to be generated between the two outer films 21a and 21b and the two inner films 25a and 25b. The air in the air chamber 23 will flow into the air filling passageway 22 via the gap generated after the hot sealing point 24b is loosed and the air is leaked out to the outside via the air filling passageway 22 to cause the air enclosure to be unable to be used. From the description mention above, for improving the structure of an air enclosure to allow the air in the air chamber to be prevented from being leaked out to cause the cushioning effect to be lost when hot sealing point thereof is thrust by the air and gradually loosed, and further to extend the air enclosure life, the present invention is proposed.